Hello everyone!

I am repairing a power supply from an electronic table lift and I hope you can help me.

The power/control unit is a switch mode power supply
Make: Dewert
Model: MC10
Input: 100 to 240 VAC, 50/60 Hz
Max Amps: 3.15 A
Intermittent Operation: 2min/18min

It powers & controls the following actuator to raise/lower the bed.
Make: Dewert
Model: Megamat MLZ 73344
Input: 24 VDC, 4.50A
Max push force: 6000N
Max Pull force: 3000N

I am supplying 120 VAC to the input and measure over 100 VDC coming out of the bridge rectifier and applied to the main transformer which is then connected to the main MOSFET transistor.
I removed and tested the main MOSFET transistor with a diode checker and I verified I could turn the MOSFET on and off, so I know it is good.

It appears that the DC - DC switching IC is not telling the main transistor to switch on and off and there is no power on the DC output side.

If I bought a new power supply what should I get?
In: 100~240 VAC
Out: 24 VDC, 4.5 A
(about 100 W)

How could I fix this?

I tested most caps and resistors and they appear good.
I suspect it is the control IC, but I can't find the part with the number I read from the IC. What I see is
IC1:
E07369
CB2201CF

IC2:
DEA2

Can someone please identify the 2 ICs on this board or tell me how I can identify them?

Top:


Bottom:


Close up photos of IC1


Close up photos of IC2


Thank you !

-Mark
Calgary, AB, T2X 3P1

 

The output of the bridge rectifier should connect to that large electrolytic capacitor and you should measure the peak of the mains voltage there - about 150V. If you have much less than that then suspect that capacitor (or, low probability, the rectifier).

 

Thank you for the advice Albert. Coming out of the the bridge rectifier I am measuring 137 VDC, so I am assuming that is the peak voltage.

Interestingly, on the DC side, I tested the double Schottky Barrier Rectifier (Hy MBR10200CT {Package=TO-220, Vf=0.9V, Forward Current=10A, Reverse Voltage150~200V} and it had one of its two diodes shorted out. So I will be replacing this diode set.

I will upload a model (schematic) of the device after I trace everything out. If I can't identify IC1 then I will have to find a suitable replacement given the model I create.

It is going to be difficult to test those little SMD components!

-Mark